The invention concerns a method and means for a security control of burners, particularly gaseous fuel burners.
From the prior art methods are known for controlling the ignition of burners, which use ionization sensors which detect whether the burner has been ignited. The ionization sensors detect a ionization current which is produced in the region of the flames generated near the surface of the burner diffuser by the combustion of the fuel which is fed to the burner. Said sensors are associated with security devices which, if there is no ionization current, that is if the fuel is not ignited during the ignition phase, or the flames are extinguished during normal operation of the burner, cut off the fuel feeding of the burner, in order to prevent fuel feeding to be continued if the ignition has not taken place, which could lead to dangerous concentrations of unburnt fuel in the combustion chamber, with a serious danger of fire or and/or explosion.
The security device may be set in such a way as to start, or restart, the ignition phase of the burner after a preestablished period of time has elapsed from the cut-off of the fuel feeding and to try again a preestablished number of times to start the burner before generating a signal of malfunction of the burner, in the event of failure of all the attempts of ignition.
The above mentioned methods, however, are not capable of detecting abnormal situations during the operation of the burner, such as, for instance, overheating of the burner, or an operative condition in which the temperature of the burner diffuser is lower than a preestablished optimal temperature, which implies usually the formation of quantities of CO and unburnt matters greater than optimal quantities.
Methods for controlling a burner are also known, wherein the feeding of the burner is controlled according to preestablished parameters, for instance the thermal power which is to be supplied to a heating plant and the temperature of the water in the water feeding the heating plant.
The above mentioned methods are not satisfactory, because the boiler is controlled without taking into account the actual operative conditions of the burner.
This invention intends to provide a method and means for a security control of a burner which are simple, reliable, less costly and capable of detecting not only ignition failures of the burners, but also abnormal operative conditions.
According to a first aspect of the present invention there is provided a method for a security control of a burner provided with a body comprising with a diffuser in which apertures for the flow of a mixture of air and fuel are made, said method comprising feeding the burner with a flow of fuel, interacting with said fuel with means capable of causing the combustion of the fuel, changing the rate of flow of said fuel, characterized in that it further comprises detecting a temperature representative of the temperature of of a surface of said diffuser in at least one zone of the diffuser, generating a signal having an intensity depending on said representative temperature.
According to another aspect of the present invention, there are provided security means for a security control of a burner including a body provided with a diffuser in which apertures for the flow of a mixture of air and fuel are made, said burnr being associated with feeding means capable of feeding the burner with a flow of fuel, ignition means capable of interacting with said fuel to cause the combustion thereof, control means capable of changing the rate of flow of said fuel, characterised in that said security means comprises temperature detecting means capable of detecting a temperature representative of the temperature of at least one zone of the surface of said diffuser and generating a signal having an intensity depending on said representative temperature.